In a display device, since a liquid crystal display panel itself cannot emit light, a backlight is needed to provide uniformly distributed light having sufficient brightness for the liquid crystal display panel so that the liquid crystal display panel can work normally.
FIG. 1 is a schematic structural diagram of a backlight in the prior art, as shown in FIG. 1, the backlight includes a driving unit and a light-emitting unit connected to the driving unit, the driving unit is used for converting a voltage signal into a driving signal (a current signal) for driving the light-emitting unit, and the light-emitting unit emits light having a certain brightness when driven by the driving signal.
However, in a practical manufacturing process of backlights, due to factors such as a process error and the like, actual properties of driving units and/or light-emitting units of some of backlights in a same batch may significantly differ from ideal properties thereof. Specifically, when a same voltage signal is applied to the backlights in the same batch, some backlights may have brightnesses distinctly different from those of the others.
For backlights in a same batch, all backlights correspond to a same maximum brightness voltage signal when reaching their respective maximum brightnesses. When the maximum brightness voltage signal is applied to the backlights in this batch, the maximum brightnesses of some backlights may not fall within a preset brightness range. For example, it is assumed that the maximum brightnesses of the manufactured backlights should be in the range of 400 nits to 500 nits as required by a customer (i.e., the backlights should have luminous brightnesses between 400 nits and 500 nits when being applied with the maximum brightness voltage signal), but, among the backlights in the same batch, some have luminous brightnesses smaller than 400 nits or larger than 500 nits when being applied with the maximum brightness voltage signal. For a backlight having a luminous brightness smaller than 400 nits, it will not be applied to a display device as it fails to meet the requirements of the customer, whereas for a backlight having a luminous brightness larger than 500 nits (i.e., a high brightness backlight), it will be applied to a display device as its maximum luminous brightness meets the requirements of the customer, i.e., its luminous brightness range can meet the requirements of the customer.
However, because the backlights whose maximum luminous brightnesses are larger than that required by the customer are applied to a display device, the display device has a poor uniformity of luminous brightness range; further, the display device including the high brightness backlight has relatively large power consumption because of excessively high brightness.